The Keck Biophysics Facility is a center for molecular biophysical research which provides Northwestern groups with advanced equipment outstanding services, specialized training, and technical expertise. Created in 1998 by Northwestern University's Center for Structural Biology with a grant from the W.M. Keck Foundation and additional support from the NIH, the Rice Foundation, and the Robert H. Lurie Comprehensive Cancer Center (RHLCCC), Keck has been one of Northwestern's Shared Resources since April 1,1999. The Keck Facility has a set of 20 advanced instruments that together allow for integrated biophysical analyses of macromolecular structure, interactions, and function. Each particular biophysical instrument, such as a circular dichroism spectrometer, a fluorimeter, or a calorimeter, provides just one or a few individual facets of a complex overall picture. Data from many individual biophysical studies - using a diverse set of particular instruments - must be combined to yield the needed comprehensive picture. In the past 5 years, the facility has been thoroughly modernized with state of the art equipment that replaced older instruments, addition of new technologies and capabilities, a modern internet-based reservation/administration system and many upgrades. In parallel, the Facility has invested in personnel training in order to provide users with outstanding technical expertise and assistance. To better accommodate the needs of our diverse user base, we are offering a flexible array of services. Besides counseling, training and assistance, full service options are also available on all the Facility's instruments. The Keck Facility currently has 506 active users from 90 research groups (students, postdoctoral fellows, and faculty who are authorized to use Keck Facility equipment). Researchers affiliated with the RHLCCC account for over 80% of the total utilization ofthe Facility. As such, the Keck Biophysics Facility is a critical resource for cancer research.